Production of manganese-steel forgings.



'No Drawing.

sur es erases r1 WINFIELD S. POTTEBIfOE NEW YORK, N. Y., ASSIGNOB TO ALLOY STEEL FGBGING COMPANY, OF 'WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE.

BODUCTIGN OF MANGANESE-TEEL FOEGINGS.

To all whom it may concern:

Be it known that I, Wmrrsno S. Porrsn, a citizen of the United States, residing at 30 Church street, in the city, county, and State of New York, have invented certain new anduseful Improvements in Production of Manganese- Steel Forgings; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use thesame. i

In the production from manganese steel of heavy forgings or even forgings which have but a moderate thickness or cross-section, the ordinary manner of heating to pro duce the necessary ductility for the forging operation, followed by rapid forming and water quenching results in certain objectionable characteristics in the final product. For example, should the blank be slowly heated through a critical range lying in the neighborhood of 700 (3., the metal will be recrystallized into a coarser structure, and by heating it to a temperature as high, for example, as 1200 C. coarse recrystallization of another character results. So also, unless properly conducted under suitable conditions, the working to finished shape may -be of such a character as to involve a reduction and pressure insufficient to satisfactorily deliver the product in the desired fine-grained condition. Furthermore, the forging may,in some instances, be finished so hot that, quenched at the finishing temperature, the steel'will have too low an elastic limit and will be liable to distortion in service and will fall below the maximum obtainable resistance to abrasive wear.

My invention is designed to obviate these difficulties and involves so conductingthe operation that the metal shallbe thoroughly worked or compressedand finished at a suitable temperature anoi t-hen immediately, quenched so that the cfiects due, to the. properv'orking or compression at th ejappro- T. priate temperature-employed shall be fixed in the finished product, This suitabletem-fv perature which determines the fixing in the finished products of the effects of there-- quired thorough" working or compression will hereinafter be termed the fixation point By working or compressing the metal at temperatures below this point (z'. 6.,

below1075 O.) and notably by continuing Specification of Letters Patent. Patgntgd l el), 20 1912, 1 Application filed May 20, 19-11. Serial No. 628,437. I

the working or compressing until tern perat-ureof about 900 C. is reached, the best results are obtained.

In the practice of my invention, the. manganese steel blank from which't-he forging or forgings'are to be produced (as, for. instance, forged gears, wheels, forgings'ifor use in railway track 'work, and other forgings of heavy cross section which involve considerable reduction or molding of the metal and which therefore require for their formation that the metal shall be in a plastic state so as to be readily worked) is heated to a temperature preferably above 1125 C.

until the constituents of the metal are in solution throughout the mass and the metal is in a plastic condition. At this temperature, the blank maybe partially formed, to such an extent that the completion'ofthe forming operation can be satisfactorily ac-..

complished at a temperature ranging from 1075 C. (the fixation point) downward to about 7 20 C, and preferably at about 900 C. which, as hereinbefore stated, is found to give the best results.

After the partial forming at-the higher temperature above 1125 C., and before the secondary or final forming is begun, the piece is brought to an equalized temperature throughout, preferablyto a temperature of about 900 C. referred to, or to suchatem-l. perature as will permit the forming operation to be finished at about 900 C. According to the character of the ultimate prodnet and the use for which itis intended, the piece is then either worked or compressed throughout to finished shape, or is worked or compressed in those portions which are to be subjected to the most severe strains to which constitute the wearing portions as, for instance, the teeth of the gear, thetread portion of a wheel, or the like. The finished shape is then immediately quenched inwalter, so that the effects of working or compressing the partsth'at are to be subjected to wear and greater strain are fixed therein. i In some instances, the procedure may be varied, with the production of 00d results and a sat-isfactory'product obtained for the particular use intended. This is notably the case where the character of the forming operation is such'as not'to requirethemaximum ductility in the blank to be formed. .Thus, the manganese steel vingot vor blank may be heated to a temperature of say,

1175 C. until in a uniform and homogeneous state, and may then be rolled or other wise formed and, after forming, rapidly cooled so as to produce a steel which retains in the cold state the carbids and other constituents in a state of homogeneous solution throughout the mass. In this condition, the blank may be heated, rapidly through the critical range lying approximately between 640 C. and 720 C. and thence upwardly to a temperature preferably not exceeding 1075 C. At the highest temperature to which it is thus brought, it may, if neces sary, be held until uniformity of temperature is established throughout the mass. In this instance, also, the temperature for completion of the finishing operation will preferably be about 900 0., and the blank will be subjected to the action of the hammer, the press, or other forming mechanism, and immediately given the intended 'finished shape. Thereupon, it will be immediately rapidly cooled so as to avoid recrystallization and loss of the fine-grained and still condition which has been produced by the sequence of the steps described.

The rapid cooling in the operations here- -inbefore described will be effected in any suitable way as, for instance,'b-y quenching .with water or by water-spraying, depending on the thickness of section and the finishing temperature, the essential being to cause the metal to cool through a range between 720? C. and about 420 C. at 'a rate sufficiently rapid to avoid separation of carbide or recrystallization.

It will be found that the quality of the metal in the finishedproduct will correspond to the characteristic features of the operation consisting, as hereinbefore inclicated, in bringing the constituents of the metal in the first place into a state -of homogeneous solution, and finally completing the working and compression at a temperature so chosen as to impart to the metal the desired'stiffness or toughness and high elastic limit.

Although a tempepature above 1125 C. has been hereinbefore mentioned as preferable for effecting the solution of the carbids and other soluble compounds of the manganese steel, the production of a manganese steel blank in a uniform austenite or gamma iron condition preparatory to the forging operation may be eflected in a longer heating operation at a temperature above the change point at about 1025 (3., in.accordance with my U. S. Patent No. 975,371, dated November 8, 1910.

What I claim is:

1. The process of producing forgings of manganese steel, which consists in forming the same from a manganese steel blank in a plastic condition and having its constituents in homogeneous solution, and completing the forming operation at a temperature below 1075 C., and finally cooling rapidly, thereby obtaining a product in which the steel has a homogeneous tine-grained structure and a high elastic limit.

2. The process of producing forgings of manganese steel, which consists in forming the same from a manganese steel blank in a plastic condition and having its constituents in homogeneous solution, and completing the forming operation at a temperature of about 900 (1, and finally rapidly cooling, thereby obtaining a product in which ,the steel has a homogeneous fine-grainedrstructure and a high elastic limit.

3. The process of producing forgings of manganese steel, which consists in forming the same from a manganese steel blank in a plastic condition and having its constituents in homogeneous solution, and completing the forming operation at a temperature be low 1075 C. and above 720 C. and finally cooling rapidly, thereby obtaining a product in which the steel has a homogeneous finegrained structure and a high elastic limit.

4. The process of producing forgings of manganese steel, which consists in heating a blank of manganese steel at'a temperature above 1125 C., working the metal, complet ing the forming operation at a temperature below 107 5 (1, and rapidly cooling.

5. The process of producing forgings of manganese steel, which consists in-heating a mass of manganese steel until the carbids have been absorbed, cooling to avoid separation of the carbids, reheating rapidly at temperatures between 640 C. and 720 (3., heating further to a temperature sufficient to impart the desired ductility, forming the blank at a temperature below 1075 C. and cooling rapidly to a temperature below 420 C.

In testimony whereof I afliX my signature, in presence of two witnesses.

JOHN C. PENNIE, MINERVA Loren.

Copies 01 this patent may be obtained for five ents each, by addressing the Commissioner of Patent-c.

Washington, D. C." 

